To do so, it relies on the fleet of servers that make up its Elastic Compute Cloud (EC2) service. When a Silk user clicks a link, the browser passes the request to EC2, which fetches all the page elements, boils them down so they won't be so taxing on the tablet's limited hardware and network abilities, then transfers the data to the tablet itself.

Mobile browsing is desperately in need of a speed boost, and Amazon deserves credit for trying to help. Unfortunately, though, I have concerns about making Amazon a middleman in the Web browsing operation.

First, I worry that Silk's design is at odds with the explosive growth of Web applications. Second, I worry that Silk will give the company a valuable view of what a huge number of people are doing on the Web.

Proxy browsing
Amazon's claims that browsing hasn't fundamentally changed since the 1990s are a bit off target. Amazon's "split browser," though, isn't the first such deviation from traditional designs.

Opera has done it for years with Opera Mini, bringing browsing to many lower-end phones that don't have the horsepower to run a full browser. Opera Mobile and desktop Opera also get a taste of proxy browsing when using "turbo" mode, which leaves much of the heavy lifting to the browser but can still help by lowering image resolution.

Amazon goes farther, though. For one thing, it retrieves Web pages in advance for cases where Silk users' aggregrate behavior makes it predictable which page they'll load next. For another, Amazon stores a lot of Web page data it knows will be needed. It's "a virtually limitless cache that can store the common files such as images, JavaScript, and Cascading Style Sheets that are used to render the Web pages you view every day," said John Jenkins, director of software development for Amazon Silk, in a YouTube video about Silk.

And according to Amazon's Silk jobs page, it uses Google's SPDY protocol for faster connections to Web servers. (That page also indicates that Silk uses the WebKit browser engine, which is no surprise given that project's role as the basis for iOS's Safari and Android's browser.)

Another speed boost involves the use of Amazon Web Services (AWS) servers with very fast connections to the Internet. "We're on a better network. Our back end has some of the fattest pipes to the Internet that you can find," said Peter Vosshall, a distinguished engineer working on Amazon Silk. Sometimes AWS even hosts Web site data directly, meaning that it doesn't even need to be retrieved from elsewhere on the Net.

What's got me worried is when Brett Taylor, principal product manager Amazon Silk, says of browsing on a tablet, "It's not meant to process and crunch a lot of heavy data."

Certainly a tablet today doesn't have as much horsepower as a laptop or desktop machine. But processing data is a big part of the new era of Web applications--the animations used in the Web version of Angry Birds, for example. And Web apps are increasingly active, with timelines that scroll to accommodate new items, pop-up messages to announce your buddy wants to chat, and inboxes updating with the latest messages. And all the work for offline Web apps means that Amazon's cloud is by definition unavailable.

This is precisely the sort of thing that's hard to do with proxy-based browsing, where a lot of the thinking happens elsewhere. No doubt Amazon will be able to update as more powerful hardware arrives, but some of its approach seems a bit backward-looking to me.

Watching you on the Web
The other fact of proxy browsing is that a third party is getting in the middle of your browsing activity. It might be a valuable intermediary in many ways--speed is good--but it's an intermediary, and that comes with some baggage.

That's because Amazon is browsing the Web on your behalf. It knows what sites you visit because it's doing the visiting for you.

That gives Amazon potentially very interesting information. What products are you searching for? What movie previews are you watching? Sounds like something an e-commerce giant might like to know, for both individual and collective data, when it comes time to place that next ad on a Kindle or drop that promotion into your inbox.

According to the Silk terms and conditions, "Personally identifiable information collected through Amazon Silk is subject to the Amazon.com Privacy Notice. And according to that notice, "We receive and store any information you enter on our Web site or give us in any other way...We use the information that you provide for such purposes as responding to your requests, customizing future shopping for you, improving our stores, and communicating with you."

Features of Amazon Silk
Screenshot by Stephen Shankland/CNET

In addition, Amazon keeps a log of what sites you've visited. "Amazon Silk also temporarily logs Web addresses--known as uniform resource locators ('URLs')--for the Web pages it serves and certain identifiers, such as IP or MAC addresses, to troubleshoot and diagnose Amazon Silk technical issues. We generally do not keep this information for longer than 30 days," the terms and conditions say.

That may not be a problem for most folks. But don't be surprised some day to see that data turning up in a court case through a search warrant or some other kind of legal process.

And when it comes to security, Amazon adds a level of complication. If you visit a site with an encrypted connection (typically shown with "HTTPS" in the address bar), the Amazon server sets up its own encrypted link to the Web site, then sets up another to the Silk browser. As long as everything goes well, you won't have a bad guy snooping your personal and business e-mail discussions, but it's not going to be end-to-end encryption.

Amazon didn't comment on a number of questions I had beyond pointing out that people can run Silk in a traditional browser mode with no proxy server if they want. Silk won't even be available until the Fire ships starting November 15, so there's still a lot of room for clarity. The way I see things, so far, though, is that revolutionizing mobile browsing isn't as simple a matter as Amazon would like people to think.

About the author

Stephen Shankland has been a reporter at CNET since 1998 and covers browsers, Web development, digital photography and new technology. In the past he has been CNET's beat reporter for Google, Yahoo, Linux, open-source software, servers and supercomputers. He has a soft spot in his heart for standards groups and I/O interfaces.
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